Bone spurs are smooth, rounded growths of extra bone that form along the edges of existing bones. On the surface of your body, they can look like hard knobs or bumps, most noticeably on knuckles, kneecaps, or the tops of feet. On X-rays and CT scans, they appear as bright white projections extending from the margins of a joint. Most bone spurs are small, and many people have them without ever knowing it.
What Bone Spurs Look Like on Your Body
When a bone spur sits close to the skin, it typically appears as a firm, rounded bump that doesn’t move when you press on it. The Cleveland Clinic describes them as “smooth lumps on the outsides of your bones.” You’re most likely to see them on joints that have little tissue covering them: the top of the kneecap, the back of the heel, or the finger joints. Sometimes the skin over a spur looks slightly swollen or puffy, but the bump itself feels distinctly hard, like bone rather than fluid.
Bone spurs in the fingers are among the most visible. When osteoarthritis breaks down cartilage in the finger joints, the body grows new bone at the joint margins. These growths, called Heberden’s nodes when they appear at the joints closest to the fingertips and Bouchard’s nodes at the middle joints, look like small, pea-sized hard bumps on either side of the joint. Over time, they can make the fingers appear enlarged, knobby, and slightly crooked. The joints often become stiffer as the nodes grow.
How Bone Spurs Look on X-Rays
On an X-ray, bone shows up bright white because it absorbs more radiation than soft tissue. A bone spur appears as a white projection sticking out from the normal edge of a bone, usually at the margin of a joint. Radiologists look for these alongside other signs of joint wear: narrowing of the space between bones (where cartilage has thinned), increased bone density just below the joint surface, and small fluid-filled cysts within the bone.
The shape varies by location. In the knee, spurs form along the inner edges of the joint and around the kneecap, looking like small lips or ridges of extra bone. In the spine, they can appear as bony bridges extending from one vertebra toward the next, sometimes narrowing the openings where nerves exit the spinal column. Heel spurs show up on a side-view X-ray as a shelf or pointed projection extending forward from the bottom of the heel bone, typically just a few millimeters long.
Despite their name, most bone spurs aren’t sharp or jagged. Spinal bone spurs, for instance, are usually rounded and smooth, closer in shape to the surface of a molar tooth than to any kind of spike. The “spur” label comes from their position as outgrowths, not from a pointy shape.
CT Scans and MRIs Show Different Details
CT scans provide the sharpest view of bone spur shape and size. Because CT uses X-ray technology from multiple angles, it creates detailed three-dimensional images of bony structures, making it the best tool for seeing exactly where a spur sits and how large it is. On a CT scan, a bone spur appears as a dense white growth with clearly defined edges.
MRI is less useful for visualizing the spur itself but far better at showing what it’s doing to surrounding soft tissue. Because nerve roots and discs have similar density on CT, it can be hard to tell whether a spur is pressing on a nerve using CT alone. MRI excels here, revealing whether a spinal bone spur is compressing a nerve root or narrowing the spinal canal. In practice, doctors often use both: CT to see the bone, MRI to see the consequences.
Where Bone Spurs Form Most Often
Bone spurs develop wherever joints experience long-term stress or cartilage loss. The most common locations are the spine, knees, hips, shoulders, hands, and feet. In the spine, they’re remarkably common with age. Studies show that spinal osteophytes appear in up to 80% of men and 60% of women over 50. Among people over 60, the prevalence climbs to 73% to 90%. Even 20% to 25% of adults between ages 20 and 45 already have some spinal osteophytes forming.
In the knee, spurs tend to cluster along the inner (medial) side of the joint and behind the kneecap, where cartilage loss is most pronounced. In the spine, they grow along the front and sides of vertebral bodies and sometimes inside the neural openings, where they can pinch nerve roots. Heel spurs grow on the underside of the heel bone at the point where the plantar fascia attaches.
What Bone Spurs Don’t Look Like
Several other conditions produce visible lumps near joints, and it helps to know the differences. Gout tophi are firm, roundish lumps that form under the skin when uric acid crystals accumulate. Unlike bone spurs, tophi can grow quite large (up to the size of a tangerine in severe cases) and sometimes develop a white head where uric acid discharge works its way toward the surface. If a lump near a joint appears to have any discharge or chalky white material, that points toward gout rather than a bone spur.
Rheumatoid nodules are another look-alike. These are firm lumps that develop in rheumatoid arthritis, typically near the elbows, fingers, or heels. They sit under the skin and can feel similar to bone spurs, but they’re composed of inflamed soft tissue rather than bone, so they’re slightly more compressible to the touch.
Ganglion cysts, common on the wrist and hand, are fluid-filled and feel rubbery or squishy when pressed. A bone spur, by contrast, is rock-hard and immovable because it’s literally part of the bone. If you can shift a lump around or compress it, it’s not a bone spur.
When Bone Spurs Cause Visible Changes
Many bone spurs never produce any visible sign at all. Spinal bone spurs, for example, grow inward rather than outward, so they’re invisible on the surface even when they’re large enough to compress nerves. You’d only know they exist through imaging or through symptoms like pain, numbness, or weakness radiating into an arm or leg.
The spurs you can actually see tend to be in the hands and feet. Finger nodes may develop gradually over months or years, starting as slight bumps and slowly becoming more prominent as the underlying joint continues to deteriorate. In the feet, a bone spur on the top of the foot or near the big toe joint can create a visible hard ridge that rubs against shoes. Heel spurs are almost never visible from the outside, since they form on the underside of the heel bone, buried beneath thick tissue.
If you notice a new hard bump near a joint, the firmness and location are the key clues. A lump that’s immovably hard, sits right at a joint line, and has developed gradually over time is the typical profile of a bone spur. Lumps that appear suddenly, feel soft, or produce redness and warmth suggest something else entirely.